21 of the most iconic photos ever taken. The image of a napalm scarred little girl running from her burning village in Vietnam is one of the most well known photographs in the world. Kim Phuc, the girl featured in the image, is now receiving free laser surgery to cover her scars, 40 years after that terrible day.
1 Oxygen: Specialized nerve cells within the aorta and carotid arteries called peripheral chemoreceptors monitor the oxygen concentration of the blood and feed back on the respiratory centers. 2  If the oxygen concentration in the blood decreases, they tell the respiratory centers to increase the rate and depth of breathing. This mechanism prevents damage to the lungs that would be caused by over-inflation. 2  Signals from higher brain centers: Nerve cells in the hypothalamus and cortex also influence the activity of the respiratory centers. 3  During pain or strong emotions, the hypothalamus will tell the respiratory centers to speed up.
The phrenic nerve is a nerve that originates in the neck (C3-C5) and passes down between the lung and heart to reach the diaphragm. It is important for breathing, as it passes motor information to the diaphragm and receives sensory information from it.There are two phrenic nerves, a left and a right one.The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves (C3-C5) in humans.here are two phrenic nerves, a left and a right one. The phrenic nerve originates mainly from the 4th cervical nerve, but also receives contributions from the 5th and 3rd cervical nerves (C3-C5) in humans.